Corresponding author: Christopher M. Wilson (
Academic editor: Michael Ohl
The male genitalia of
Wilson CM, Smith-Herron A, Cook JL (2016) Morphology of the male genitalia of Brachymyrmex and their implications in the Formicinae phylogeny. Journal of Hymenoptera Research 50: 81–95. doi:
The ant genus
Santschi (1923) provided the last revision of the group, designating many new species and subspecies. His descriptions, however, are of little value, as they are short and include few comparative characters. In his revision Santschi erected the subgenus
The genus has a wide diversity of life histories. Most species are generalist nesters that nest in leaf litter, under stones, or under bark; at least two species have a distinct replete caste; while others are arboreal nesting under epiphyte mats or in small plant cavities. By contrast, the closely-related
As our understanding of ant evolution progresses, the need for additional taxonomic and systematic information is increasing. The primary source for morphological characters in ants is worker morphology. This trend is easy to understand as workers are ubiquitous in the environment, often being the only caste collected and certainly the most prevalent. Queens and males on the other hand are less-frequently encountered, as they are usually within nests or produced only for brief periods. The reproductive casts have thus been largely neglected. Males are largely ignored, and therefore represent an untapped source of morphological characters for taxonomic and phylogenetic use. Moreover, when collected, males may be difficult or even impossible to associate with their workers. However, males may be associated through careful collecting and molecular phylogenies. A recent movement among ant researchers has been to pay more attention to males, both when collecting in the field and unassociated males (
The most useful character for males are arguably the genitalia, and males, like workers, range in size from the scanning electron microscopy
Here we present methods for dissection and permanent storage via slide mounting of small ant genitalia, with an additional option for muscle fixture and the ability to clear structures for
For this study we sampled 16 species/morphospecies of Sam Houston State University Entomology Collection John T. Longino collection
The procedures for the unstained whole mounts are as follows. The terminal segments of male reproductive organs were removed with a surgical scalpel and size 000 insect pins. Tissues were transferred and presoaked in a 20% sodium hydroxide
The procedures for stained whole mounts are as follows. The terminal segments of male reproductive organs were removed with a surgical scalpel and size 000 insect pins. In order to examine the insertion and attachment sites for all muscles, excised tissues were not dissolved. Hydration of reproductive tissues were initiated in 70% ethanol and regressed to a final wash in deionized water. Prepared tissues were stained for 20 minutes in Harris Hematoxylin (without counterstain), and washed in an acid alcohol de-stain for 5–10 seconds. Stained tissues were then dehydrated with ethanol through an ascending graded series, cleared in xylene and permanently mounted with Damar Balsam mounting media. Examination of prepared tissue mounts follows the description above. The figures presented here are grouped by similar morphology and grouping statements accompany the respective figures.
The terminology herein follows
The paired penisvalvae of
Ectal views of the right penisvalvae of
As the base of the valvura is produced laterally, it may be referred to as the “lateral apodeme” (Fig.
Two main conformation patterns can be seen in the penisvalval morphology among the
External genitalia of
Paramere, volsella, and penisvalva of
The lateral carina of conformation 2 is incomplete being broken apically of the lateral apodeme into an anterior portion, which is continuous with the lateral apodeme, and a posterior portion that is raised dorsally above the blade of the valviceps (Fig.
Paramere, volsella, and penisvalva of
Paramere, volsella, and penisvalva of
Paramere, volsella, and penisvalva of
The volsella of
Ectal views of the volsella in
The modification to the lateral carina of the valviceps seen in both conformation groups seem to be related to the method in which the volsella rests against the valviceps
The telomeres are separated from the basimere by a membrane. Of the structures associated with the genital capsule, the telomeres of
Our findings demonstrate that males of this genus may offer more taxonomic information for understating the evolution within the genus, and for species delineations than their worker counterparts. The morphology of the penisvalva lateral carina displayed in the two conformation groups seen in
Within
Future researchers collecting
The authors would like to thank Brendon Boudinot for reviewing earlier versions of this manuscript, his comments substantially improved this work. We would also like to thank Jack Longino for contributing much-needed specimens without which much of this genus would still be a mystery.
Specimen locality data
Specimen locality data
Locality data for dissected specimens.